1. Field of the Invention
The present invention relates to a method and system of correcting an output voltage sensing error of a low voltage direct current to direct current (DC-DC) converter, and more particularly, to correcting an output voltage sensing error of a low voltage DC-DC converter to adjust a difference between a value obtained by sensing an output voltage of a low voltage DC-DC converter and a reference value to adjust the low voltage DC-DC converter, thereby improving control accuracy.
2. Description of the Related Art
A low voltage DC-DC converter (LDC) is an element that reduces a high voltage to a low voltage, charges a low-voltage battery (or subsidiary battery) with the low voltage and supplies power to electrical components of a an environmentally friendly vehicle. The LDC is adjusted to follow a voltage reference value provided by an LDC controller (microcomputer) to output a voltage. More specifically, the LDC controller is configured to output a voltage reference value to determine an output voltage of the LDC. A pulse width modulation (PWM) driver (PWM IC) to operate a switching element disposed in the LDC to receive the voltage reference value and a value obtained by sensing the output voltage of the LDC and adjusts the value based on the voltage reference value.
In particular, a factor that determines control accuracy of the output voltage may be determined by LDC output voltage sensing accuracy (e.g., a resistance error), resolution of the voltage reference value (which is related to the performance of the microcomputer that implements the LDC controller) and a degree of loss due to parasitic impedance components of a bus bar of an LDC output. For example, in digital control, LDC output voltage sensing accuracy may be improved by correcting a scale or offset value per sample with respect to a reference value at the end of a line. In the case of analog control, however, it is difficult to improve accuracy of an output voltage sensing value input to an analog IC unless resistance error in a circuit for sensing the output voltage is corrected. In other words, improved sensing accuracy in analog control is difficult to achieve unless hardware of the output voltage sensing circuit is adjusted to a new sensing circuit having a minimal resistance error, which increases costs.
Recently, various countries have developed strict requirements for LDC voltage control errors through authentication requirements related to LDC control of environmentally friendly vehicles and provide subsidies and tax benefits when authentication is achieved by satisfying such requirements. Therefore, research and development for LDC control accuracy improvement are needed.
The matters disclosed in this section are merely for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that the matters form the related art already known to a person skilled in the art.